The present invention relates to a structure of a thin, rotary head device for use in a magnetic recording and reproducing apparatus of a high density, e.g. VTR (video tape recorder), and also relates to a magnetic recording and reproducing apparatus using the rotary head device.
For example, a conventional rotary head device is disclosed in Japanese Patent Laid-Open No. 181151/1988, in which the motor of the rotary head device is disposed under a fixed drum. According to the structure disclosed therein, the motor drives the rotary drum through a shaft which is supported rotatably at the center of the fixed drum.
In the rotary head device of such structure, it is difficult to decrease the height of the apparatus because the motor is disposed under the fixed drum.
As a structure for overcoming such drawback there is proposed a structure of a rotary head device in Japanese Patent Laid-Open No. 150125/1980, in which a motor is disposed within a rotary drum to reduce the height of the rotary head device to a great extent. According to this structure, the motor is supported and fixed by a shaft which is fixed at the center of a fixed drum.
However, the above structure of the rotary head device in which the central shaft is fixed is different in machining and assembling method from a rotary shaft type structure which has widely been adopted so far, and therefore the conventional manufacturing equipment for rotary shaft type rotary head devices cannot be used.
Besides, it is necessary that the potential level of the rotary drum be grounded in order to suppress the noise contained in a playback signal provided from the head. In conventional rotary shaft type rotary head devices, an earth brush, is brought into contact with the center of the rotary shaft to ground the rotary drum. On the other hand, in a fixed shaft type rotary head device in which a shaft is fixed to a fixed drum, the position for contact of an earth brush is only outside the outside diameter of the fixed shaft. In the fixed shaft type, therefore, the sliding speed at the earth brush contact portion is high, thus causing problems such as abrasion of the earth brush and increase of the driving torque.